NEW OMICRON RECOMBINANTS

• Genetic mutations are drivers of the evolution of organisms but not all mutations are functional.
• Mutations with functional advantage tend to emerge over time more than those without.
• Viruses could rarely evolve by exchanging large fragments of the genome called recombination.
• Recombination events are rare & occur when two viruses/lineages co-infect a cell.
• Recombinations result in viruses that have a mixed genome, each part of the mix derived from the parent genomes which recombined.

• SARS-CoV-2 has the potential to recombine, several recombinant lineages were observed during the pandemic.
• The PANGO network, an open, global consortium of researchers, provides a system for naming different lineages of SARS-CoV-2 detected & assigned a lineage name.
• Recombinant lineage names start with the letter 'X', followed by letters that indicate the order of their detection.
• XA, a recombinant lineage between B.1.1.7(Alpha) & B.1.177 lineages of the virus, was the first recombinant lineage of SARS-CoV-2 & was detected in the United Kingdom in early 2021.
• Recombinant lineages were detected & designed, including lineage XB, which was detected in US & lineage XC was detected in Japan & is a recombinant of B.1.1.7 & the AY.29 sublineage of Delta.
• It is important to track SARS-CoV-2 recombinant lineages as they could lead to the emergence of lineage.
• Genomic surveillance for monitoring the emergence of lineage is central to monitoring variants.

• A recombinant lineage XBB was emerging in Asia.
• This lineage comes out of the recombination of two Omicron sublineages BJ.1 & BA.2.75.
• Early data suggest that this variant can evade a wide range of monoclonal antibodies & protection acquired through vaccination.
• More research will be needed to conclusively assess the growth advantages of the XBB lineage, where initial data suggest that the lineage may potentially outcompete previously circulating Omicron sublineages.
• XBB lineage is present in multiple countries including India.
• XBB was significantly emerging concurrently with a surge in COVID-19 infections in Singapore.
• XBB & its sublineages account for over 50% of the genomes from Singapore in recent weeks.
• The earliest genome sequence of XBB in the global database was from Kolkata.
• With a total of 94 genomes, India has the highest number of XBB genomes to date.
• The increasing prevalence of XBB across India was not associated with a spike in infections.
• Of the 300-odd sub-lineages of Omicron in circulation, recent weeks have seen BQ.1 sub-lineages emerging in Europe, the US, and India recently detected BQ.1 from Pune.

• Genomic surveillance provides the key to detecting & monitoring emerging lineages including recombinant lineages of SARS-CoV-2.
• It is reassuring that vaccination will be effective in preventing severe outcomes of COVID-19.
• Additional research is required to answer the questions regarding how the emerging lineages will impact the trajectory of the pandemic.
• Wider use of time-tested & effective methods like masks, ventilation & avoidance of crowds to prevent infections for the COVID-19 pandemic is not over yet.